Inhibitor



Patented June 9, 1931 PATENT OFFICE UNITED STATES RUSSELL L. JENKINS, JOHN H. KARRH, AND CAMPBELL R. MOGULLOUGH, OF ANNISTON,

ALABAMA ASSIGNORS TO SWANN' RESEARCH,

INC A. CORPORATION OF ALABAMA.

INHIBITOR No Drawing.

This invention relates to the storage and transportation of phosphoric acids in such dilutions as attack the iron in steel or iron containers or drums.

It has been proposed to prevent the corrosion and dissolution of steel or iron drums or containers used for the storage and transportation of phosphoric acid, by dissolving in the acid a material capable of precipitating a protective coating on the steel. This precipitate may be accomplished in the presence or absence of an acid regulator. The precipitated protective coating is usually a metal below iron and above mercury in the electromotive series, such as arsenic, while the acid regulator is usually an organic substance, such as pyridine bases, crude anthracene, sulphite lye resins, wash acids from refining hydrocarbons, etc. Other combinations which give similar effects are stannous tin and various organic compounds of a similar nature to those enumerated above.

Thls inventlon has as an ob ect the preventlon of corroslon or dlssolution of iron containers by means of phosphoric acid,

other than by plating the surface with a metal. A further object is to provide a corrosion inhibitor which is cheap as well as non-poisonous and odorless, or one which may be easily removed from the acid, so that the acid is not rendered permanently unfit for food purposes.

These objects are accomplished by the following inventionQ We have found that the dissolution or corrosion of iron and steel can be substantially prevented by the addition of a combination of aldehydes with ionizable compounds of high atomic weight halogens. The aldehydes which we have found to work may be either aliphatic aldehydes, such as formaldehyde or formalin; aromatic aldehydes, such as benzaldehyde; or heterocyclic aldehydes, such as furfural. The high atomic weight halides include the alkali metal salts of hydriodic or hydrobromic acid. The salts of hydrochloric or hydrofluroic acid, i. e. low atomic weight halogens, have been found not to work satisfactorily. On the other hand we have obtained good results in the above combinaor bromide.

Application filed February 3, 1930. Serial No. 425,712.

tion with ionizable organic halides of high molecular weight such as. quinoline ethiodide, which is a polar compound ionizing in aqueous solution as does potassium iodide Other examples of ionizable organic halides of high molecular weight are tetraethyl ammonium iodide or tetraethyl ammonium bromide. On the other hand such halides as ethyl iodide or bromide, which do not ionize in aqueous solution and are not polar compounds, have been found not to Work in the above combination.

Our invention may be practiced as follows:

To a solution of phosphoric acid of 75% strength add .003% by weight of potassium lodide, and 0.10% by weight of furfural. Place in an ordinary steel shipping or storage container. It will be observed that the rate of penetration of the steel by the acid is negligibly small compared with the corrosion proceeding in the case of the pure acid. Another method for practicing our invention is as follows :-To a solution of phosphoric acid of 7 5% strength, add 0.05% of sodium bromide and 0.1% of furfural. Place in an ordinary steel shipping contamer. It will be observed that approximately the same rate of penetration has taken place as in the case of the former nnxture.

We have also found that the following mlxture is efiicacious in preventing corrosionz Per cent Quinoline ethiodide 0. 003 Furfural 0. 300

Per cent Potassium iodide 0. 003 F ormalin (formaldehyde) 0. 100

In each example cited above, the effect of the two substances mentioned is not merely the aggregate efl'ect of the twosubstancestaken alone, but a considerably enhanced effect.

-tration of the acid into the steel as cslc For example, we have found that the M by the loss in weight in the presence of .003% of quinoline ethiodide alone is at the rate of .024 inches r year,-while in the case of 0.300 a of rfural it is .016 inches per year; e have found that when .003% of quinoline ethiodide and 0.300% of furfural are added to an acid, the penetration is at the rate of .0023 inches per year. Similar efiects are obtained in the case of other combinations of furfural with organic and inor anic iodides.

All of the materia utilized, with the exception of formalin, are quite unobjectionable to phosphoric acid when used in food products, and are comparatively cheap. An discoloration of the acid, if objectionab e, filtering through decolorizing carbon.

While the proportions of the inhibitors given above are satisfactory for ordinary service, they may be considerably varied without departing from the s irit of the invention. In general, it may said that increasing the concentration of the inhibitor decreases the amount of penetration, while decreasing the concentration increases the penetration.

What we claim is:

1. A composition for inhibitin the corrosive action of phosphoric aci on iron and steel, comprising an aldeh do and an ionizable compound of a high atomic weight halogen.

2. The addition of an aldehyde, and an ionizable compound of a high atomic weight halogen to phosphoric acid to inhibit its corrosive action on iron and steel.

3. An inhibitor for protecting iron and steel from the corrosive action of phosphoric acid of a concentration as much as 5%, comprising substantially 0.1% of furfural and 0.003% of potassium iodide of the weight of the acid dissolved in the acid.

4. The dissolving of furfural and an iodide in phosphoric acid in inhibitory concentrations to inhibit the corrosive action of the acid on iron and steel.

5. A composition for inhibiting the corrosive action of phosphoric acid on iron and steel comprising furfural and an ionizable compound of a high atomic wei ht halogen. In testimony whereof we, tussnnn L. JENKINS, JOHN H. KARRH, and CAMPBELL R. MoOULLoUoH, afiix our si natures.

RUSSELL L. JENK NS.

JOHN H. KARRH.

CAMPBELL R. MGCULLOUGH.

may be easily removed by 

